Higher folate requirements during pregnancy to support growth and development are well established but it is unknown what metabolic changes occur in 1-carbon metabolism to provide sufficient nucleotides for DNA/RNA synthesis. Periconceptual folic acid (FA) supplementation and fortification of the food supply have been shown to reduce the risk of pregnancies with neural tube defects but conversely expose women to high FA intakes for extended periods of time. The purpose of this cross-sectional study is to establish if physiological adaptations occur in folate metabolism in response to pregnancy or higher intakes of FA typically consumed among women during the reproductive period. A convenience sample of thirty-two women (n=8/group) were recruited to compare the total concentrations and forms of folate (tetrahydrofolate [THF], 5-methylTHF, 5-formylTHF and 5, 10-methenylTHF) in red blood cells in four groups: a) pregnant women (PW, 30-36 weeks gestation) taking 1.0 mg of FA b) non-pregnant women (NPW) taking 0 mg of FA c) NPW taking 1.0 mg FA and d) NPW taking 5.0 mg FA. Blood samples were taken at a single time point and compared across groups. Total red blood cell concentrations were measured using both microbiological assay and liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis. LC/MS/MS analysis was used to determine folate form concentrations.